This invention relates generally to the field of devices for the teaching of the metric system, and more particularly to an improved toy suitable for use by children of relatively tender years whereby they may acquire a degree of familiarity with the metric system, as a part of their preschool exposure. Devices of this general type are known in the art, and the invention lies in specific constructional details which enable the device to be used by children who are just beginning to read.
The prior art includes U.S. Pat. No. 176,735 granted to W. F. Bradbury May 2, 1876. It comprises a hollow metric box adapted to be filled by a solid metric cube, with a separable one centimeter cube located in one corner thereof.
The McCourt U.S. Pat. No. 480,119 granted Aug. 2, 1892 features a metric cube, a one-tenth part of which is formed as a hinged construction resembling a carpenter's rule.
The Nogues U.S. Pat. No. 4,322,567 granted June 1, 1982 discloses a somewhat similar, if more complicated construction which is used as a teaching aid for arithmetic, metric and analytical geometry as well as elementary algebra. It is formed by a cubic block array comprising a plurality of different sized blocks arranged in rows and columns. The cubic block array has a base array of ten-by-ten blocks commencing with a one centimeter block and progressing in x and y rows with increasing length blocks and overlying arrays of the same pattern but progressively increasing in height.
The devices described in the above patents are not without utility, but have serious limitations in the form of complexity of manufacture and difficulty from the standpoint of manipulation by children of preschool age. Further, because of the large number of parts in such devices, the educational content and concept, contemplated by the use thereof is not readily imparted to such children.